1. Field of the Invention
The present invention relates to a lock mechanism for a stage apparatus which locks a movable stage when the movable stage, which is freely movable in a specific plane, is in a non-operational state.
2. Description of the Prior Art
Examples of the aforementioned conventional lock mechanism for a movable stage are disclosed in, e.g., Japanese Patent No. 3431020 and Japanese unexamined Patent Publication Nos. H10-39352, 2004-163649 and H11-271833.
The lock mechanisms disclosed in these documents are each applied to a hand-shake correction apparatus (image-shake correction apparatus/image-shake reduction apparatus) of a camera. Each of theses lock mechanisms is provided with a lock recess which is formed on a removable stage that supports either a correction lens or an image pickup device, and is further provided with a lock pin capable of being engaged and disengaged in and from the lock recess. When no handshake correction is performed, the movable stage is locked by making the lock pin engaged in the lock recess.
However, in the lock mechanism such as disclosed in the above-mentioned documents, a clearance is inevitably created between the lock pin and the lock recess, and accordingly, the movable stage cannot be locked firmly so as to have no play. Namely, even if the movable state is locked by the engagement of the lock pin in the lock recess, play corresponding to the amount of clearance between the lock pin and the lock recess inevitably occurs.
Additionally, in the lock mechanisms disclosed in the above-mentioned documents, the lock pin and a member for moving the lock pin are large in size in a direction orthogonal to the movable stage, which increases the lengths of the lock mechanism and the hand-shake correction apparatus in the optical axis direction.
In addition, there has been a problem in that the movable stage must be moved to a position where the lock pin and the lock recess face each other when the lock pin is brought into the lock recess to be engaged therewith.